Iran is set tomorrow to execute a football player's mistress accused of murdering his wife, a lawyer for the woman has told the Guardian.

Shahla Jahed, whose case has become a cause celebre in the Islamic republic, was found guilty of the 2002 murder of Laleh Saharkhizan, the wife of Naser Mohammadkhani, a football legend who rose to fame in the mid-1980s and coached Tehran's Persepolis club.

Jahed, who has been held in Tehran's notorious Evin prison for nine years, was sentenced to death on the basis of her confession, which she later repeatedly retracted at her public trial.

Earlier this year Tehran caused an international outcry after Sakineh Mohammadi Ashtiani, a 43-year-old woman, was sentenced to death by stoning for adultery.

Iran initially postponed Jahed's execution as a result of the outcry over Ashtiani's case. But speaking on the phone from Tehran, Abdolsamad Khorramshahi, Jahed's lawyer, said: "I've been informed by the Iranian judiciary that she will be executed in Tehran's Evin prison at 5am on Wednesday."

Following the murder, Jahed was arrested as the prime suspect, but she refused to talk for nearly a year. Mohammadkhani was also imprisoned for several months on charges of complicity but was finally released after the authorities said Jahed had confessed to committing the crime alone.

Jahed told the judge at her public trial: "If you want to kill me, go ahead … if you send me back there [where her confessions were taken], I'll confess again and not only will I confess to killing her but I'd also confess that I killed those who have been killed by others," she continued. She then repeatedly reiterated that she was innocent and that she had not committed any crime.

Activists in Iran widely suspect that Jahed was forced to confess to the stabbing. The news of Jahed's pending execution outraged human rights activists, who have campaigned for several years to stop Iran from killing her.

Karim Lahidji, the president of the Iranian League for Human Rights, said: "Shahla Jahed has never had a fair trial in Iran and has always insisted that she is innocent. Unfortunately, she's a victim of a misogynous society. Although Sakineh Mohammadi Ashtiani's case is about adultery, her case is similar to that of Shahla Jahed because both are victims of the flaws of the Iranian judicial system."

He added: "We are approaching the Human Rights Day on 10 December and once again Iran is planning to execute another woman. That's a clear signal that Iran wants to challenge the world on human rights issues."

Mohammadkhani was in Germany when the killing happened, but it emerged later that he was "temporarily married" to Jahed, a practice allowed under Shia Islam. Temporary marriage or "sigheh", as it is known in Iran, allows men to take on wives for as little as a few hours to years on the condition that any offspring are legally and financially provided for. Critics of the tradition see it as legalised prostitution.

Shahla Jahed's case drew huge attention when Iran took the unprecedented decision of holding her trial in public.

In 2005 a documentary about her case and her affairs with the footballer showed footage from her public trial. The documentary, Red Card, was subsequently banned by Iran.

Amnesty International has been campaigning for Jahed's sentence to be overturned since 2005 and has urged Iran to stop her execution.

Its UK director, Kate Allen, said: "We are opposed to the death penalty in all cases as the ultimate cruel and inhuman punishment. But on top of that, Shahla may not have received a fair trial. She retracted her confession, made after months in solitary confinement, leading to fears that it was coerced. This is sadly far from unusual in Iran, in our experience. Her claim was never properly investigated. This execution could – and should – be stopped on humanitarian or judicial grounds."

According to Iranian law, Shahla Jahed's life could still be spared if the family of the murdered wife pardons her before 5am.